Abstract: In seismic survey for icy waters, streamers are towed behind a vessel under the water's surface to avoid ice. GPS readings may not be consistently obtained because the ice prevents a tail buoy with a GPS receiver from trailing from streamer at the surface. Instead, a device tows on the streamer under the water's surface. The streamer's absolute position is tracked by intermittently bringing the towed device toward the surface so GPS readings can be obtained. The streamer's absolute position can then be used in conjunction with compass readings and can correlate various seismic sensor signals obtained along the streamer during the survey. The compass readings can be corrected for declination using declinometer readings, which can be compensated for iron effects from the vessel or other device carrying the declinometer.

Abstract: Computer instructions for determining coordinates for nodes on a wire secured to tow lines of a floating vessel for analyzing geological formations is provided. The computer instructions can use sensors in communication with a processor to determine the coordinates of nodes and provide azimuths tangential to the wire. A library of nominal values for polynomial coefficients, a library of known distances along the wire, and a library of preset limits can be stored in a data storage. The computer instructions can: receive sensor information, compute bearing, reorient the coordinates, rotate the azimuth, construct a polynomial algorithm, compute the azimuth, form a residual, compute updated differences until the residual is within preset limits, calculate local coordinates for nodes, and rotate the local coordinates from the local coordinate system to the projected coordinate system.

Abstract: In seismic survey for icy waters, streamers are towed behind a vessel under the water's surface to avoid ice. GPS readings may not be consistently obtained because the ice prevents a tail buoy with a GPS receiver from trailing from streamer at the surface. Instead, a device tows on the streamer under the water's surface. The streamer's absolute position is tracked by intermittently bringing the towed device toward the surface so GPS readings can be obtained. The streamer's absolute position can then be used in conjunction with compass readings and can correlate various seismic sensor signals obtained along the streamer during the survey. The compass readings can be corrected for declination using declinometer readings, which can be compensated for iron effects from the vessel or other device carrying the declinometer.